| Description: | The Process Management Interface (PMI) has been used for quite some time as
a means of exchanging wireup information needed for interprocess
communication. Two versions (PMI-1 and PMI-2) have been released as part of
the MPICH effort. While PMI-2 demonstrates better scaling properties than its
PMI-1 predecessor, attaining rapid launch and wireup of the roughly 1M
processes executing across 100k nodes expected for exascale operations remains
challenging.
PMI Exascale (PMIx) represents an attempt to resolve these questions by
providing an extended version of the PMI standard specifically designed to
support clusters up to and including exascale sizes. The overall objective of
the project is not to branch the existing pseudo-standard definitions - in
fact, PMIx fully supports both of the existing PMI-1 and PMI-2 APIs - but
rather to (a) augment and extend those APIs to eliminate some current
restrictions that impact scalability, and (b) provide a reference
implementation of the PMI-server that demonstrates the desired level of
scalability. |
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